Adhesion of glass fibers to rubber with adhesive layer comprising a cresol-formaldehyde-resorcinol resin

ABSTRACT

An aqueous alkaline dispersion of a rubbery vinyl pyridine copolymer and a water soluble, heat reactable o-cresol-formaldehyde-resorcinol resin, in certain amounts, is useful in forming an adhesive for bonding glass fiber reinforcing elements or cords to rubber compounds or stocks. After dipping the glass fiber cord in the one-step adhesive dip, the coated cord is heated to dry it and heat cure or heat set the adhesive on the cord. Thereafter, the adhesive containing glass fiber cord is combined or laminated (calendered) with a curable rubber compound and the resulting assembly is cured to form a composite in which the glass fiber cord is bonded to the rubber by means of said adhesive.

This application is a division of copending U.S. patent application Ser.No. 523,645 filed Nov. 13, 1974, entitled "ADHESION OF GLASS FIBERS TORUBBER" and now U.S. Pat. No. 3,955,033 granted May 4, 1976.

OBJECTS

An object of the invention is to provide a composite of a glass fiberreinforcing element adhesively bonded to a rubber compound, e.g., glassfiber tire cords adhesively bonded to provide carcass plies and beltplies for making tires. Another object is to provide glass fiberreinforcing elements, e.g., such as those used in the belt and thecarcass plies of tires, with a minor amount of an adhesive so that theadhesive containing elements may subsequently be bonded to rubber oncuring. A further object is to provide a method for bonding glassfibers, particularly glass fiber textiles, fibers, cords and so forth,to rubber compounds using a single dip. A still further object is toprovide a glass fiber or cord adhesive dip composition. These and otherobjects and advantages of the present invention will become moreapparent to those skilled in the art from the following detaileddescription and working examples.

SUMMARY OF THE INVENTION

According to the present invention it has been discovered that acomposition comprising an aqueous alkaline dispersion of 100 parts byweight (dry) of a rubbery vinyl pyridine copolymer, from about 8 to 75parts by weight of a heat reactable water solubleo-cresol-formaldehyde-resorcinol resin, and from about 250 to 1100 partsby weight of water, is very useful as a treating, dipping or coatingmaterial for use in bonding glass fiber reinforcing elements to rubbercompounds. Preferably, the o-cresol is reacted with the formaldehydebefore the resorcinol is reacted to form the resin to avoid freeo-cresol in the dip and, also, possibly in the cord. Sufficient alkalinematerial such as aqueous KOH or NaOH may be added to the dispersion (orto one or more of the ingredients of the dispersion before mixing themtogether) to obtain the desired pH, prevent coagulation of the latex andto provide for stabilization. This will vary with the pH of the resinand the latex, all of which may vary from batch to batch. Since theamount of each compound may vary, the amount of alkaline materialrequired can also vary. After drying the adhesive on the glass fiberreinforcing element to remove water and to heat cure or heat set theadhesive on the element, the adhesive containing element can then becombined or calendered with a curable rubber compound and the resultingassembly cured, usually in a mold, to provide a laminate exhibiting goodadhesive properties. The use of o-cresol in making the cord dips givesmore stable dips and adhesives which are softer and have a lower modulusand which may provide for better tire performance by giving less cordbreakage. Moreover, o-cresol is an economical monomer to employ.

The present method involves only one dipping step, and the process ormethod can be varied to provide the desired pick-up or solids on thecord by varying the concentration of the dip or the speed of the cordthrough the dip to give the amount needed to develop the requisiteadhesive bond. Thus, while the cord can be run through successive dipsof the same or varying amounts of the above materials to get the desiredbuildup, this is unnecessary as satisfactory results can be accomplishedin one dip. Pre or post dips of other adhesive compositions areunnecessary when using the present aqueous adhesive dip.

DISCUSSION OF DETAILS AND PREFERRED EMBODIMENTS

The glass fiber reinforcing element or cord comprises a plurality ofsubstantially continuous and parallel glass fibers or monofilaments. Thereinforcing element or fibers contain little or no twist. In otherwords, twist is not intentionally applied to the element or fibers; theonly twist, if any, in the element or fibers is that occasioned onpassing through the glass fiber processing apparatus and on packaging orwinding up the cord to form a bobbin or spool. However, in a continuousprocess, the elements can proceed directly from the glass processingapparatus, can be dipped in the aqueous adhesive cord dip, dried, andgiven a twist of about 1.5 turns per inch thereafter. The elements thenare woven into tire fabric having about one quite small pick thread orelement, nylon or polyester, which may be a monofilament, per inch andcalendered with a rubber ply or skim stock. The glass fiber reinforcedply stock is then ready to be used in the manufacture of a tire or forother purposes.

Glass compositions useful in making the fibers for the reinforcingelement or glass tire cord are well known to the art. One of thepreferred glasses to use is a glass known as E glass and described in"Mechanics of Pneumatic Tires," Clark, National Bureau of StandardsMonograph 122, U.S. Dept. of Commerce, issued November, 1971, pages241-243, 290, and 291. The number of glass filaments or fibers employedin the glass fiber reinforcing element or cord can vary considerablydepending on the ultimate use or service requirements. Likewise, thenumber of strands of glass fibers used to make a glass fiber reinforcingelement or cord can vary widely. In general, the number of filaments inthe glass fiber reinforcing element or cord for a passenger car tire canvary from about 500 to 3,000 and the number of strands in thereinforcing element can vary from 1 to 10, preferably the number ofstrands is from 1 to 7 and the total number of filaments about 2000. Arepresentative industry tire cord known as G-75 (or G-75, 5/0) has 5strands each with 408 glass filaments. Another representative cord knownas G-15 has a single strand containing 2040 glass filaments. In thisconnection reference is made to Wolf, "Rubber Journal," February, 1971,pages 26 and 27 and U.S. Pat. No. 3,433,689.

Shortly after the glass fibers are formed they are usually sized (byspraying or dipping and so forth and air drying) with a very smallamount of fractional amount of weight of a material which acts as aprotective coating during processing and handling of the glass fibers informing the strands or reinforcing elements and during packaging. Duringthe subsequent dipping in the aqueous adhesive tire cord dip, it isbelieved that the size is not removed. Materials for use as sizes forglass fibers are well known to the art. It is preferred to use a silaneas a size, especially a silane which has groups which can bond orcoordinate chemically or physically with at least parts of the surfaceof the glass of the glass fiber and with at least one or more of thecomponents of the glass fiber aqueous adhesive cord dip. A very usefulsize to employ on the glass fibers is gamma-aminopropyl triethoxysilane, or similar aminoalkyl alkoxy silanes, which, when applied to theglass fibers, hydrolyzes and polymerizes to form a poly(aminosiloxane)in which a portion of the polymer is attached to the glass and anotherportion contains amine groups (having active hydrogen atoms) forreaction with components of the cord dip such as the CFR resin or thevinyl pyridine copolymer compound. Glass fiber sizing compounds areknown, and some compositions are shown in U.S. Pat. Nos. 3,252,278;3,287,204; and 3,538,974.

The type of rubber latex used in the tire cord dip bath of thisinvention is a latex of a copolymer of a vinyl pyridine and a conjugateddiolefin having 4 to 6 carbon atoms. The rubber latex is of the typedescribed in U.S. Pat. No. 2,561,215 and comprises an aqueous dispersionof a copolymer of 50 to 95 percent by weight of a conjugated diolefinhaving 4 to 6 carbon atoms, 5 to 40 percent of a vinyl pyridine and 0 to40 percent of a styrene. Examples of suitable vinyl pyridines are2-vinyl pyridine, 4-vinyl pyridine, 2-methyl-5-vinyl pyridine, and5-ethyl-2-vinyl pyridine.

In practicing this invention, it is usually preferred to use a latex ofa terpolymer of from about 60 to 80% by weight butadiene-1,3, about 7 to32% styrene and abut 5 to 22% of 2-vinyl pyridine having a total solidscontent of around 30 to 50% by weight. Also, blends of latices may beused such as a blend of a butadiene-1,3/2-vinyl pyridine rubberycopolymer latex and a butadiene-1,3/styrene rubbery copolymer latex or ablend of a butadiene-1,3/styrene/2-vinyl pyridine rubbery copolymerlatex and a butadiene-1,3/styrene rubbery copolymer latex so long as thepercent by weight ratio of total monomers in the copolymers is withinthe ranges as specified above. The pH of the latices should be similarand the surfactants and stabilizers including freeze stabilizers shouldbe compatible to avoid coagulation on blending or mixing of the latices.The polymers from these latices have Mooney viscosities ML-4 min. at212°F. of from about 40 to 120. Further disclosures of rubbery vinylpyridine copolymer latices may be found in U.S. Pat. Nos. 2,615,826 and3,437,122.

The water soluble, heat reactable o-cresol-formaldehyde-resorcinol resinis made by reacting formaldehyde with o-cresol and resorcinol in aqueousmedia using sodium hydroxide and/or potassium hydroxide and the like asa catalyst. The mol ratio of the o-cresol to the resorcinol is fromabout 1:1 to 1:5. The formaldehyde is used in a molar excess over thetotal mols of o-cresol and resorcinol. Preferably, the mol ratio of thetotal mols of the o-cresol plus the resorcinol to the mols offormaldehyde is from about 1:1.4 to 1:2.0. Such resins cure by theapplication of heat. See "The Chemistry of Phenolic Resins," Martin,John Wiley & Sons, Inc., New York, 1956. The ratio dry of the vinylpyridine copolymer to the resin is from about 100:8 to 100:75 parts byweight, preferably from about 100:10 to 100:55 parts by weight.

Water is used in an amount sufficient to provide for the desireddispersion of the rubber or latex particles, and for the solution of theo-cresol-formaldehyde-resorcinol resin, to obtain the desiredviscosities, and for the proper solids content to get the necessarypickup of solids on and penetration between the fibers of the cord.

Based on 100 parts by weight (dry weight) of the vinyl pyridine rubbercopolymer, or blend of the same, the aqueous alkaline dip comprises therubber, from about 8 to 75 parts by weight of the water soluble heatreactable o-cresol-formaldehyde-resorcinol resin and from about 250 to1100 parts by weight of water. A minor amount by weight of wax (naturalor synthetic) based on the rubber solids in the dip may be added to thedip, for example about 2 to 10 parts by weight of wax per 100 parts(dry) of the rubber. An example of a useful wax is a wax emulsion, ablend of paraffin microcrystalline waxes, total solids about 56.3%,active solids 50%, Wax Emulsion No. 5, General Latex & ChemicalCorporation.

In order to provide data for the tire cord adhesive of this invention, astandard single-cord H-pull test is employed to determine the staticadhesion at room temperature and above of the adhesive-coated glass tirecord to rubber. All the data submitted herein including the workingexamples which follow are based upon identical test conditions, and alltest specimens are prepared and tested in the same way generally inaccordance with ASTM Designation: D 2138-67.

To apply the latex adhesive to the glass fiber cords in a reliablemanner, the cords are fed through the adhesive dip bath while beingmaintained under a small predetermined tension and into a drying ovenwhere they are dried under a small predetermined tension (to preventsagging without any appreciable stretching). As the cords leave the oventhey enter a cooling zone where they are air cooled before the tensionis released. In each case the adhesive-coated cords leaving the dip aredried in the oven at from about 200° to 600°F. for from about 5-300seconds, preferably at from about 400° to 500°F. for from about 90 to 30seconds. The time the cord remains in the one-step adhesive is about afew seconds or so or at least for a period of time sufficient to allowwetting of the cord and at least substantial total impregnation of thefibers of the cord. The drying or curing of the adhesive treated glassfiber cord may be accomplished in one or more ovens at different timesand temperatures.

The single-cord H-pull test is then employed to determine the staticadhesion of the dried adhesive coated glass fiber cords to rubber. Ineach case the rubber test specimens are made from the same standard typeof vulcanizable rubber composition comprising rubber, reinforcing carbonblack and the customary compounding and curing ingredients.

In every case the cords to be tested are placed in parallel positions ina multiple-strand mold of the type described in the single-cord H-pulladhesion test ASTM designated D 2138-67, the mold is filled withunvulcanized rubber of the above composition, the cords being maintainedunder a tension of 50 grams each, and the rubber is cured for 20 minutesat around 305°F. to the elastic state. Each rubber test specimen is 1/4inch thick and has a 3/8 inch cord embedment.

After the rubber has been cured, the hot cured rubber piece is removedfrom the mold, cooled and H-test specimens are cut from said piece, eachspecimen consisting of a single cord encased in rubber and having eachend embedded in the center of a rubber tab or embedment having a lengthof around 1 inch or so. The specimens are then aged at least 16 hours atroom temperature. The force required to separate the cord from therubber is then determined at room temperature or 250°F. using an INSTRONtester provided with specimen grips. The maximum force in poundsrequired to separate the cord from the rubber is the H-adhesion value.

Cords or fabric coated with the adhesive of the present invention usingthe one-step or single dip of this invention can have from about 10 to40% by weight (dry) solids of the adhesive dip on the cord based on theweight of the cord and can be used in the manufacture of carcasses,belts, flippers and chafers of radial, bias, or belted-bias passengertires, truck tires, motorcycle and bicycle tires, off-the-road tires andairplane tires, and, also, in making transmission belts, V-belts,conveyor belts, hose, gaskets, rubbers, tarpaulins and the like.

While the adhesive containing glass fiber reinforcing element can beadhered to a vulcanizable blend of natural rubber, rubberycis-polybutadiene and rubbery butadiene-styrene copolymer by curing thesame in combination together, it is apparent that the heat curedadhesive containing glass fiber reinforcing element can be adhered toother vulcanizable rubbery materials, by curing or vulcanizing the samein combination with the rubber, such as one or more of the foregoingrubbers as well as nitrile rubbers, chloroprene rubbers, polyisoprenes,polybutadienes, vinyl pyridine rubbers, acrylic rubbers,isoprene-acrylonitrile rubbers and the like and mixtures of the same.These rubbers can be mixed with the usual compounding ingredientsincluding sulfur, stearic acid, zinc oxide, magnesium oxide,accelerators, antioxidants and other curatives, rubber compoundingingredients and the like well known to those skilled in the art for theparticular rubbers being employed.

The following examples will serve to illustrate the invention with moreparticularity to those skilled in the art. In these examples the partsare parts by weight unless otherwise indicated.

EXAMPLE I

a. Solution A was prepared by mixing the following components:

    ______________________________________                                        o-Cresol         5.1g      .047 mol                                           37% Formaldehyde in H.sub.2 O                                                                  12.0g     .148 mol                                           1N NaOH (4% NaOH in H.sub.2 O)                                                                 2.0g                                                                          19.1g                                                        ______________________________________                                    

This solution was aged 3 days at room temperature (about 25°C.) beforefurther use. Solution B was prepared by dissolving 5.1g (.046 mol)resorcinol in 13.3g of water.

Solution B was slowly added to solution A at room temperature and wellmixed. This mixture was slowly added to 244 g vinyl pyridine latex (1)to produce a dip with about 40.8% total solids content. This dip wasaged 20 hours before use and called Dip 1.

b. A control dip was prepared by mixing together:

    ______________________________________                                        Resorcinol   11.15g      0.101 mol                                            1N NaOH      2.0g                                                             H.sub.2 O    53.73g                                                           37% Formaldehyde                                                                           13.12g      0.161 mol                                            ______________________________________                                    

The resulting RF resin solution was aged 5 minutes and then mixed with244g of the above noted vinyl pyridine latex. This dip had a solidscontent of about 35.8% and was designated as Dip 2.

Greige glass fiber cords (2) were passed through the dips and then intoa long tube in which hot air was blown in a direction opposite to themovement of the cords. The temperature where the air entered the tubewas 60° to 90°F. higher than the temperature at the exit end of thetube. The highest temperature during the drying, curing or heat settingof the dipped cords was about 425°F., and the time in the tube was about45 seconds. After said drying and curing, the adhesive treated cordswere laminated with standard type rubber compounded stocks A or B, andmolded, and the resulting assembly was cured for 20 minutes at 305°F.After curing, the assembly was removed from the mold, cooled and testedaccording to the H-adhesion test described supra. The H-adhesions of thecords, cord tensiles and folding test results are shown in Table Ibelow:

                  Table I                                                         ______________________________________                                                         Dip 1    Dip 2                                               ______________________________________                                        DPU, % (3)         21.4        18.7                                           Tensile, lbs. (4)  65.0       71.7                                            H-Adhesion, lbs.                                                              Rubber Stock A                                                                 At room temp. (about 25°C.)                                                              44.2       42.9                                             at 250°F.  26.7       25.6                                             At room temp. after aging                                                                       34.4       25.6                                              24 hrs. at 300°F. in H.sub.2 O                                         in sealed container                                                         Rubber Stock B                                                                 At room temp. (about 25°C.)                                                              25.6       30.5                                             at 250°F.  16.9       20.9                                             At room temp. after aging                                                                       16.8       11.7                                              24 hrs. at 300°F. in H.sub.2 O                                         in sealed container                                                         Folding Test (5)   2877       44                                               Notes: (1) Aqueous alkaline dispersion of a rubbery terpolymer of about       65.5 parts by weight of butadiene-1,3, 23.5 parts of styrene and 11 parts     of 2-vinyl pyridine, 41% by weight total solids (about 39% by weight          rubber solids, balance surfactant, stabilizer, etc.), Mooney viscosity        ML-4 min. at 212°F. = about 80-110, emulsion polymerized, freeze       stable.                                                                       (2) G-15 cord, E glass, single strand tire cord of 2040 glass filaments,      Owens-Corning Fiberglass Corporation which may contain a size composition     (3) Dip pickup. Percent by weight of glass. Pickup determined by ignition     loss.                                                                         (4) Test used was ASTM D 2970. Undipped G-15 cords of E glass exhibit         tensiles of 43-44 pounds. Tests on adhesive dipped and heat set cords.        (5) Number of folds to break on Tinius Olson paper folding instrument         (M.I.T. Folding and Endurance Tester), ASTM-D-2176-69. Tests on adhesive      dipped and heat set cords.                                               

    Rubber Stocks Used In Above Tests                                             ______________________________________                                        Stock A                 Parts by Weight                                       Natural rubber          46.64                                                 Butadiene-styrene rubbery copolymer,                                                                  38.5                                                   average 23.5% bound styrene,                                                  SBR-1500, emulsion polymerized                                               Polybutadiene, solution polymerized                                                                   15.0                                                   BD, about 93% cis-1,4, Raw Mooney                                             ML-4 at 212°F. about 40-50                                            Carbon black, fast extrusion furnace                                                                  45.0                                                  Hydrated silica, "Hi-Sil" 233, PPG                                                                    15.0                                                   Industries, Inc.                                                             "BLE" 25 antioxidant, a high temperature                                                              2.0                                                    reaction product of diphenylamine and                                         acetone, Naugatuck Chemical Division                                          of Uniroyal                                                                  Processing oil, a blend of highly                                                                     5.0                                                    aromatic petroleum fractions                                                 Zinc oxide              3.0                                                   Stearic acid            1.5                                                   "Cohedur" RL, a 1:1 mixture of resorcinol                                                             4.7                                                    and "Cohedur" A (the pentamethyl                                              ether of hexamethylol melamine) which                                         is a colorless, viscous liquid which                                          liberates formaldehyde on heating.                                            Naftone, Inc.)                                                               N-tert-butyl-2-benzothiazole-sulfenamide,                                                             1.2                                                    "Santocure" NS, Monsanto Chemical Co.                                        Sulfur                  3.0                                                   Stock B                 Parts by Weight                                       Natural Rubber          50                                                    Butadiene-styrene rubbery copolymer                                                                   50                                                     average 23.5% bound styrene,                                                  SBR-1502, emulsion polymerized                                               High abrasion furnace   35                                                     carbon black                                                                 "Endor", activated zinc 0.5                                                    salt of pentachloro-thiophenol,                                               peptizing agent, du Pont                                                     "Circosol" 2XH, naphthenic type oil                                                                   7.0                                                    Sun Oil Company                                                              Zinc Oxide              3.0                                                   Stearic Acid            1.0                                                   "Agerite Spar", a mixture of mono-,                                                                   1.0                                                    di- and tri-styrenated phenols,                                               antioxidant,                                                                  R. T. Vanderbilt Co., Inc.                                                   "Picco 100", alkyl aromatic polyindene resin,                                                         2.0                                                    reinforcing and processing oil,                                               Pennsylvania Industrial Chemical Corp.                                       Diphenylguanidine       0.5                                                   N-oxydiethylene benzothiazole-                                                                        0.9                                                    2-sulfenamide                                                                Sulfur (insoluble)      2.60                                                  ______________________________________                                    

EXAMPLE II

The method of this example was similar to that of Example I, above,except that the dip cords were passed through an oven in a few secondsat a relatively high temperature, ca. 600°F. Moreover, there were addedto the dip about 6 parts of wax on 100 parts of latex solids prior todipping. The results on testing are shown below in Table II:

                  Table II                                                        ______________________________________                                                         Dip 1    Dip 2                                               ______________________________________                                        DPU, % (3)         15.3       14.6                                            Dip Stability: Viscosity, cps                                                 Storage Time, Days                                                              1                21.5       9.5                                              19                25.5       20.5                                             40                28.0       24.2                                            Tensile, lbs. (4) orig.                                                                          62.9       66.0                                            Tensile, lbs. after humidity                                                                     61.5       64.8                                             aging, 3 days at 174°F. in                                             H.sub.2 O in sealed container                                                H-Adhesion, lbs.                                                               Rubber Stock A                                                                Room temperature  37.0       31.5                                             at 250°F.  23.4       21.1                                             At room temp. after aging                                                                       31.3       19.5                                             24 hrs. at 300°F. in H.sub.2 O                                         in sealed container                                                           Rubber Stock B                                                                Room temperature  22.5       20.9                                             at 250°F.  13.7       14.1                                             At room temp. after aging                                                                       12.7       12.7                                             24 hrs. at 300°F. in H.sub.2 O                                         in sealed container                                                          Peel Adhesion, lbs. (6)                                                        Room temperature  29.2       15.9                                             at 250°F.  22.0       13.5                                             At room temp. after aging                                                                       7.4        1.1                                              24 hrs. at 300°F. in H.sub.2 O                                         in sealed container                                                          ______________________________________                                         Notes:                                                                        (6) Peel adhesion is Chemstrand Strip Adhesion which is modified ASTM         D-2630-71.                                                               

EXAMPLE III

Films were prepared from Dips 1 and 2. Before casting the films 20 gramsof a 10% aqueous solution of the potassium salt of isomerized rosin acid(a surfactant, Dresinate 214, Hercules Incorporated) were added to each50g of dip to make the films continuous. After casting the films werecured for 10 minutes at 310°F. The results of the test on the films areshown below in Table III:

                  Table III                                                       ______________________________________                                                      Dip 1     Dip 2                                                 ______________________________________                                        Modulus, psi                                                                   5%             335         569                                               10%             455         738                                               15%             536         756                                               20%             591         800                                               25%             626         844                                               Tensile, psi    653         1354                                              Elongation, %   368         100                                               ______________________________________                                    

Dips were prepared similar to Dip 1 of Example I, above, except that theo-cresol, resorcinol and formaldehyde were mixed together. The glasscords were greige Owens-Corning Fiberglas Corporation or PPG Industries,Incorporated glass cords where 5 yarns were plied together and dipped togive a 75 5/0 tire cord construction. The cords were predried at 215°F.and cured at 425°F. The weight ratio of o-cresol to resorcinol in theresin was 25:75, 37.5:62.5 and 50:50. Similar dips were prepared inwhich the o-cresol was replaced with m-cresol, p-cresol, p-ethyl phenoland p-methoxy phenol. The dip pickups varied from about 11 to 18%. TheH-adhesions and cord tensiles for the dips containing the resins madewith o-cresol were on the average higher than the H-adhesions and cordtensiles for the dips where the resin was made with the othersubstituted phenols.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. A method for adhering aglass fiber reinforcing element to a rubber compound which comprisedtreating said element with a composition consisting essentially of anaqueous alkaline dispersion of 100 parts by weight of a rubbery vinylpyridine copolymer, from about 8 to 75 parts by weight of a watersoluble, heat reactable o-cresol-formaldehyderesorcinol resin, and fromabout 250 to 1100 parts by weight of water, heating said treated elementat a temperature and for a time sufficient to remove essentially all ofthe water from said composition and to provide said element with a heatcured adhesive in an amount of from about 10 to 40% by weight (dry)based on the weight of said reinforcing element, combining said driedand heat cured adhesive containing reinforcing element with anunvulcanized vulcanizable rubber compound, and vulcanizing the same, themol ratio of the o-cresol to the resorcinol being from about 1:1 to 1:5and the mols of formaldehyde being in excess of the total mols of theo-cresol and resorcinol in the resin, and said composition coating andat least substantially totally impregnating said element.
 2. A methodfor adhering a glass fiber reinforcing element to a rubber compoundwhich comprises treating said element with a composition consistingessentially of an aqueous alkaline dispersion of 100 parts by weight ofa rubbery vinyl pyridine copolymer, from about 8 to 75 parts by weightof a water soluble, heat reactable o-cresol-formaldehyde-resorcinolresin and from about 250 to 1100 parts by weight of water, heating saidtreated element at a temperature of from about 200° to 600°F. for fromabout 5 to 300 seconds to remove essentially all of the water from saidcomposition and to provide said element with a heat cured adhesive in anamount of from about 10 to 40% by weight (dry) based on the weight ofsaid reinforcing element, combining said dried and heat cured adhesivecontaining reinforcing element with an unvulcanized vulcanizable rubbercompound, and vulcanizing the same, the mol ratio of the o-cresol to theresorcinol being from about 1:1 to 1:5 and the mols of formaldehydebeing in excess of the total of the o-cresol and resorcinol in theresin, said composition coating and at least substantially totallyimpregnating said element.
 3. A method according to claim 2 where saidrubbery vinyl pyridine copolymer is a copolymer of from about 60 to 80%by weight of butadiene-1,3, from about 7 to 32% by weight of styrene,and from about 5 to 22% by weight of 2-vinyl pyridine.
 4. A methodaccording to claim 3 where said o-cresol is reacted with theformaldehyde prior to the reaction with the resorcinol to form saidresin and where the mol ratio of the total mols of the o-cresol plus theresorcinol to the formaldehyde is from about 1:1.4 to 1:2.0.
 5. A methodaccording to claim 3 where said o-cresol-formaldehyde-resorcinol resinis used in an amount of from about 10 to 55 parts by weight and wheresaid composition contains additionally a minor amount by weight of waxbased on the rubbery copolymer.
 6. A method according to claim 2 wheresaid treated element is heated at a temperature of from about 400° to500°F. for from about 90 to 30 seconds.